/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 25228
 * Date: 2024-08-03
 * Time: 17:22
 */
public class LinkedList {

    static class ListNode{
        public int val;
        public ListNode prev;
        public ListNode next;

        public ListNode(int val){
            this.val=val;
        }
    }
    public ListNode head;
    public ListNode last;




    //头插法
    public void addFirst(int date) {
        ListNode node = new ListNode(date);
        if (head == null) {
            head = node;
            last = node;
        } else {
            node.next = head;
            head.prev = node;
            head = node;
        }
    }
    //尾插法
    public void addLast(int date){
        ListNode node =new ListNode(date);
        if(head==null){
            head=node;
            last=node;
        }else{
            last.next=node;
            node.prev=last;
            last=node;
        }
    }
    //任意位置插入,第一个数据节点为0号下标
    public void addIndex(int index,int data){
        if(index<0||index>size()){
            return;
        }
        if(index == 0) {
            addFirst(data);
            return;
        }
        if(index == size()) {
            addLast(data);
            return;
        }
        ListNode node=new ListNode(data);
        ListNode cur=head;
        for (int i = 0; i < index; i++) {
            cur=cur.next;
        }
        cur.prev.next=node;
        node.prev=cur.prev;
        node.next=cur;
        cur.prev=node;
    }
    //查找是否包含关键字key是否在单链表当中
    public boolean contains(int key){
        ListNode cur=head;
        while(cur!=null){
            if(cur.val==key){
                return true;
            }
            cur=cur.next;
        }
        return false;
    }
    //删除第一次出现关键字为key的节点
    public void remove(int key){
        ListNode cur =head;
        while(cur!=null){
            if(cur.val==key){
                if(cur==head){
                    head=head.next;
                    if(head==null){
                        head.prev=null;
                    }else{
                        last=null;
                    }
                } else {
                    cur.prev.next = cur.next;
                    if(cur.next == null) {
                        last = cur.prev;
                    }else {
                        cur.next.prev = cur.prev;
                    }
                }
                return;
            }else {
                cur = cur.next;
            }
        }
    }
    //删除所有值为key的节点
    public void removeAllKey(int key){
        ListNode cur =head;
        while(cur!=null){
            if(cur.val==key){
                if(cur==head){
                    head=head.next;
                    if(head==null){
                        head.prev=null;
                    }else{
                        last=null;
                    }
                } else {
                    cur.prev.next = cur.next;
                    if(cur.next == null) {
                        last = cur.prev;
                    }else {
                        cur.next.prev = cur.prev;
                    }
                }
            }else {
                cur = cur.next;
            }
        }
    }
    //得到单链表的长度
    public int size(){
        ListNode cur=head;
        int count=0;
        while(cur!=null){
            count++;
            cur=cur.next;
        }
        return count;
    }
    public void display(){
        ListNode cur=head;
        while(cur!=null){
            System.out.println(cur.val);
            cur=cur.next;
        }
    }
    public void clear(){
        head=null;
        last=null;
    }
}
